(if
(not
(equal 0.0 c))
(progn
(setq a (- (angle c p1) (angle c p2)))
(setq ap1 (polar c (- (angle c p1) (/ a 3)) (distance c p1)))
(setq ap2 (polar c (- (angle c ap1) (/ a 3)) (distance c p1)))
means if it haves a centerpoint from arcentity calculate angle between lines c,p1 and c,p2. (p1 and p2 are start and endpoint of arc.)
In the case I have dubble arc in a polyline it doenīt works idea, because I miss p2